Dithiophosphate compounds



Reissued June 15, 1937 UNITED STATES Re. 20,411 PATENT OFFICE 20,411DITHIOPHOSPHATE COMPOUNDS poration of Maine No Drawing. Original No.1,949,629, dated March 6, 1934, Serial No. 270,796, April 1'7, 1928.Application for reissue March 2, 1936, Serial 8 Claims.

This invention relates to new compounds which are adapted for varioususes, more particularly as uct is a yellow, moderately viscous oil. Thereaction may be represented by the following accelerators in thevulcanization of rubber. equation:

0119201210 s 011010110 s oonwnm 2 OHmOHO SNa+S;Ol =2NaCl+(CHa)zOH0S-Sz-S 0011mm There have been heretofore described certain Example 2compounds made by the reaction of phosphorous pentasulphide on organicoxygen containing compounds, such as alcohols and phenols. It has beendetermined that compounds of this character are di-thiophosphates ordi-thiophosphoric acids of either the alkyl or aryl type. We

5 have now discovered that compounds of this character either in theform of the free di-thiophosphoric acid or salts thereof may be causedto react with chorine and with certain chlorine compounds producingcommercially valuable substances.

A large variety of chlorine products are adaptable for our purpose, butwe find that in general chlorine compounds containing no metallicelement are eminently suitable. For example, we

have made many reaction products of di-thiophosphates with sulphurmono-chloride, sulphur xii-chloride, ethylene di-chloride, ethylchlorcarbonate, ethylene chlorhydrin, amyl chloride, phosphoroustri-chloride, chlorine and phosgene. We find that the reaction isgeneral and that chlorine compounds other than those specifically namedare available for our purpose. The following are examples of theoperation of our invention which results in the formation of newcompounds of the character above referred to.

Example 1 To a well agitated 40 per cent solution of sodiumdi-iso-propyl di-thiophosphate in water and cooled with ice, sulphurmono-chloride is slowly added and the temperature is not allowed toexceed C. The relative proportions of the reacting ingredients are twomolecules of di-thiophosphate and one molecule of sulphur monochloride.The oily upper layer which separates A similar product may be obtainedby using the free di-thiophosphoric acid instead of its sodium salt. Totwo molecules of free di-iso-propyl dithiopnosphoric acid is added onemolecule of sulphur mono-chloride and the mixture kept cool aspreviously, hydrochloric acid being evolved,- Whereas in Example 1sodium chloride is formed and remains in the mixture as such. Theproduct thus obtained from the reactions of either Example 1 or Example2, reacts with aniline and similar amines at ordinary temperature. Uponmixing such product with aniline, for example, there is no appreciableevolution of heat, but the solution on standing for some time depositscrystals of a compound thereof. The reaction product has been found tobe a moderately active accelerator at 258 F. and an extremely activeaccelerator at 288 F.

Example 3 1 per cent excess of sulphur mono-chloride is added slowlywith rapid agitation to 99 per cent di-ethyl di-thiophosphoric acid,cooled in an ice bath. The reaction is very vigorous at the start andtowards the end the mixture is heated to 50 C. until the evolution ofhydrochloric acid has ceased. The liquid is cooled, treated with dilutesodium carbonate solution until it is neutral to litmus, washed withwater and dried by shaking with anhydrous sodium sulphate.

Example 4 The reaction product of ethylene di-chloride and ammoniumdi-iso-propyl di-thiophosphate is prepared by heating the two substancesin proper proportion for several hours. The reaction may be representedas occurring in two stages by the following two equations:

Hr-Ol from the mixture is dissolved in ether, dried by means ofanhydrous sodium sulphate, and freed from ether by evaporation. Thereaction prodsnmjnmoi Example 5 The ethyl formic ester of di-iso-propyldi-thiophosphoric acid may be readily prepared by pro viding a solutionin acetone of ammonium di-isopropyl di-thiophosphate, agitating the samevigorously and adding thereto a theoretical amount of ethylchlorcarbonate, while keeping the solution cool. The reaction mixture isallowed to stand for some time after which the ammonium chloride formedis separated from the solution and washed with acetone. The solution isdistilled at reduced pressure to remove the acetone and the liquid thusobtained washed with water and dried. 7

Example 6 Glycol di-iso-propyl dithiophosphate may be prepared byproviding a 40 per cent solution in water of sodium di-iso-propyldi-thiophosphate and ethylene chlorhydrin in equimolecular proportionsand allowed to stand for several hours. The solution is then heatedslowly causing a liquid to separate from the solution and thetemperature is maintained at about C. for one hour. The product iswashed with water containing sodium carbonate, then with water andsubsequently dried with anhydrous sodium sulphate.

Example 7 Phosphorous tri-[di-iso-propyl di-thiophosphate] may beproduced by adding the theoretical amount of phosphorous tri-chloride topure di-iso-propyl di-thiophosphoric acid in a vessel equipped withcooling means and a reflux condenser. At the beginning of the reactionhydrochloric acid is rapidly evolved and when the reaction slows downthe mixture is heated to 70 C. for about three hours or until theevolution of hydrochloric acid ceases. The reaction may be representedby the following equation:

We have described above the preparation of a number of substances all ofwhich may be readily made and which when tested have proven to beaccelerators of vulcanization of rubber. These compounds are merelyrepresentative members of a large group of compounds which may be formedin accordance with the principles of our invention. Although thedi-thiophosphoric acids or phosphates mentioned above are alkylcompounds it is to be understood that our invention is not limited tothe alkyl di-thiophosphates, but the aryl compounds are equally adaptedfor our purpose. For example, a compound is readily formed by the directreaction of sulphur chloride and diphenyl di-thiophosphoric acidbysimplymixingthe same with agitation and cooling. Similarly, other arylcompounds of similarconstitution maybe used.

We have prepared a large number of compounds utilizing the chlorinecompounds mentioned in the specific examples given above and in additionhave successfully used sulphur di-chloride, amyl chloride, chlorine andphosgene. The chlorine compound is quite analogous to the sulphurmonochloride compound but contains two less sulphur atoms. Since such alarge variety of chlorine compounds are available for this reaction Weconclude that the reaction is general and may be carried out with almostany available chlorine compound which does not contain a metallicelement. All of the substances mentioned, including chlorine, may bedefined as compounds capable of chemically removing hydrogen from thedithiophosphates and such terminology Wherever it may occur is intendedto have this meaning.

It will be apparent that our invention is of broad scope and is not tobe limited by the specific examples given above, but the scope of ourinvention is set forth in the claims appended hereto. In the claims theterm di-thiophosphate is intended to include both the aryl and the alkylcompounds, and the salts thereof as well as the free acids.

What we claim is:

1. A vulcanizable rubber composition containing a vulcanization agentand a vulcanization accelerator comprising the reaction product of a.di-thiophosphate and a chlorine compound of sulphur.

2. A vulcanizable rubber composition containing a vulcanization agentand a vulcanization accelerator comprising the reaction product of adi-thiophosphate and sulphur mono-chloride.

3. A vulcanizable rubber composition containing a vulcanization agentand a vulcanization accelerator comprising the reaction product of adi-thiophosphate and sulphur mono-chloride, having most probably thefollowing structural formula:

RO\ s S\P/OR RO/ SSz-S oa where R represents an alkyl or aryl group.

4. The reaction product of a di-thiophosphate and a chlorine compound ofsulphur.

5. The reaction product of a di-thiophosphate and sulphur mono-chloride.

6. The reaction product of a di-thiophosphate and sulphur mono-chloridehaving most probably the following structural formula:

RO S S OR P P 30 SSzS on where R represents an alkyl or aryl group.

7. A polythiophosphate compound having the following formula:

in which R is an alkyl group and :n represents a whole number greaterthan 1 and less than 5.

CHARLES J. ROMIEUX. KENNETH D. ASHLEY.

